From d941f3db1db79fd921b6aadb75b2dc06d18386db Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Mon, 9 Dec 2019 22:40:26 -0800
Subject: [PATCH] go/types: remove satisfyContract - now implemented via
 instantiate

Change-Id: I1561d57709a996112b39aa8a15826387ea062e29
---
 src/go/types/contracts.go | 61 ---------------------------------------
 1 file changed, 61 deletions(-)

diff --git a/src/go/types/contracts.go b/src/go/types/contracts.go
index 20d5d7e59d..a7966891f6 100644
--- a/src/go/types/contracts.go
+++ b/src/go/types/contracts.go
@@ -224,64 +224,3 @@ func (check *Checker) typeConstraint(typ Type, why *string) bool {
 	}
 	return true
 }
-
-// satisfyContract reports whether the given type arguments satisfy a contract.
-// The contract may be nil, in which case it is always satisfied.
-// The number of type arguments must match the number of contract type parameters.
-// TODO(gri) missing: good error reporting
-func (check *Checker) satisfyContract(contr *Contract, targs []Type) bool {
-	if contr == nil {
-		return true
-	}
-
-	assert(len(contr.TParams) == len(targs))
-
-	// A contract is represented by a list of interfaces, one for each
-	// contract type parameter. Each of those interfaces may be parameterized
-	// with any of the other contract type parameters.
-	// We need to verify that each type argument implements its respective
-	// contract interface, but only after substituting any contract type parameters
-	// in that interface with the respective type arguments.
-	//
-	// TODO(gri) This implementation strategy (and implementation) would be
-	// much more direct if we were to replace contracts simply with (parameterized)
-	// interfaces. All the existing machinery would simply fall into place.
-
-	for i, targ := range targs {
-		iface := contr.ifaceAt(i)
-		// If iface is generic, we need to replace the type parameters
-		// with the respective type arguments.
-		// TODO(gri) fix this
-		if IsParameterized(iface) {
-			// check.dump("BEFORE iface(%s) => %s (%s)", targ, iface, fmt.Sprintf("%p", iface))
-			iface = check.subst(token.NoPos, iface, contr.TParams, targs).(*Interface)
-			// check.dump("AFTER  iface(%s) => %s (%s)", targ, iface, fmt.Sprintf("%p", iface))
-		}
-		// use interface type of type parameter, if any
-		// targ must implement iface
-		if m, _ := check.missingMethod(targ, iface, true); m != nil {
-			// check.dump("missing %s (%s, %s)", m, targ, iface)
-			return false
-		}
-		// targ's underlying type must also be one of the interface types listed, if any
-		if len(iface.types) > 0 {
-			utyp := targ.Underlying()
-			// TODO(gri) Cannot handle a type argument that is itself parameterized for now
-			switch utyp.(type) {
-			case *Interface, *Contract:
-				panic("unimplemented")
-			}
-			ok := false
-			for _, t := range iface.types {
-				// if we find one matching type, we're ok
-				if Identical(utyp, t) {
-					ok = true
-					break
-				}
-			}
-			return ok
-		}
-	}
-
-	return true
-}